Couple of questions... What size PV system do you have? 4 kWp I would assume at that price? Where does the 12p come from in your savings calculations?
One other thing about the Tesla Powerwall is that I can run completely off grid during power cuts, which is a nice feature. I see it says about 4 hours worth of energy using light appliances? Have you tested it?
Still find it hard to justify a battery set up - the longevity of the battery is of course another issue to consider with predicted life cycles of circa 10 years...whereas the Solar PV system longevity is of course not an issue other than inverter lifespan.
The panels are 6.4kW and the inverter is 6kW.
You can set the reserve power (the lowest the battery will discharge to in normal use) in the Tesla between 0 and 100%. The Tesla max output rate appears to be 5kW. I have it at 10% reserve just to avoid short term blips. If the battery was fully charged when the outage happened, it would have 13kWh available to run off grid if there was no solar input. I also have a 3kW generator wired to a switch box as back up, we have a lot of overhead power lines and trees in our area. My kids call me a “doomsday prepper” so, yes I have tested it, there’s an “off grid” feature on the app. There’s also a nice feature called “storm watch” where depending on local weather forecasts the battery will automatically top up ahead of the event,
The 12p is the Octopus Go tariff between 0030 and 0430.
